Rapidly growing global population adds significant strains on the fresh water resources. Consequently, saline water is increasingly tapped for crop irrigation. Meanwhile, rapid advancement of ...nanotechnology is introducing more and more engineered nanoparticles into the environment and in agricultural soils. While some negative effects of ENPs on plant health at very high concentrations have been reported, more beneficial effects of ENPs at relatively low concentrations are increasingly noticed, opening doors for potential applications of nanotechnology in agriculture. In particular, we found that cerium oxide nanoparticles (CeO2NPs) improved plant photosynthesis in salt stressed plants. Due to the close connections between salt stress tolerance and the root anatomical structures, we postulated that CeO2NPs could modify plant root anatomy and improve plant salt stress tolerance. This study aimed at testing the hypothesis with Brassica napus in the presence of CeO2NPs (0, 500 mg kg−1 dry sand) and/or NaCl (0, 50 mM) in a growth chamber. Free hand sections of fresh roots were taken every seven days for three weeks and the suberin lamellae development was examined under a fluorescence microscope. The results confirmed the hypothesis that CeO2NPs modified the formation of the apoplastic barriers in Brassica roots. In salt stressed plants, CeO2NPs shortened the root apoplastic barriers which allowed more Na+ transport to shoots and less accumulation of Na+ in plant roots. The altered Na+ fluxes and transport led to better physiological performance of Brassica and may lead to new applications of nanotechnology in agriculture.
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•Cerium oxide nanoparticles caused plant root anatomical changes.•The modification of root apoplastic barriers resulted in better salt stress tolerance by Brassica.•Cerium oxide nanoparticles led to different Na+ distribution in Brassica.•Salt stress also resulted in altered uptake and accumulation of cerium oxide nanoparticles by Brassica.
Cerium oxide nanoparticles altered the formation of root apoplastic barriers and improved the salt stress tolerance of Brassica.
Aims
Mineral-associated organic matter, mainly derived from microbial by-products, persists longer in soil compared to particulate organic matter (POM). POM is highly recalcitrant and originates ...largely from decomposing root and shoot litter. Theory suggests that root traits and growth dynamics should affect carbon (C) accumulation into these different pools, but the specific traits driving this accumulation are not clearly identified.
Methods
Twelve herbaceous species were grown for 37 weeks in monocultures. Root elongation rate (RER) was measured throughout the experiment. At the end of the experiment, we determined morphological and chemical root traits, as well as substrate induced respiration (SIR) as a proxy for microbial activity. Carbon was measured in four different soil fractions, following particle-size and density fractionation.
Results
Root biomass, RER, root diameter, hemicellulose content and SIR (characteristic of N
2
-fixing Fabaceae species), were all positively correlated with increased C in the coarse silt fraction. Root diameter and hemicellulose content were negatively correlated with C in the POM fraction, that was greater under non N
2
-fixing Poaceae species, characterized by lignin-rich roots with a high carbon:nitrogen ratio that grew slowly. The accumulation of C in different soil pools was mediated by microbial activity.
Conclusions
Our results show that root traits determine C input into different soil pools, mediated primarily by microbial activity, thus determining the fate of soil organic C. We also highlight that C in different soil pools, and not only total soil organic C, should be reported in future studies to better understand its origin, fate and dynamics.
Despite their proven efficacy in treating neurological disorders, especially Parkinson's disease, deep brain stimulation (DBS) systems could be further optimized to maximize treatment benefits. In ...particular, because current open-loop DBS strategies based on fixed stimulation settings leave the typical parkinsonian motor fluctuations and rapid symptom variations partly uncontrolled, research has for several years focused on developing novel “closed-loop” or “adaptive” DBS (aDBS) systems. aDBS consists of a simple closed-loop model designed to measure and analyze a control variable reflecting the patient's clinical condition to elaborate new stimulation settings and send them to an “intelligent” implanted stimulator. The major problem in developing an aDBS system is choosing the ideal control variable for feedback. Here we review current evidence on the advantages of neurosignal-controlled aDBS that uses local field potentials (LFPs) as a control variable, and describe the technology already available to create new aDBS systems, and the potential benefits of aDBS for patients with Parkinson's disease.
► Adaptive DBS (aDBS) strategies might improve control over parkinsonian disturbances. ► aDBS systems automatically adjust stimulation by analyzing the individual patient’s condition. ► A suitable control variable for aDBS are local field potentials (LFPs) recorded from the implanted DBS electrode. ► Algorithms for closing the DBS loop are still under development. ► aDBS could allow patients to become less dependent on their caregivers.
A greenhouse study comparing the physiological responses and uptake of coffee (Coffea arabica L.) plants to foliar applications of zinc sulfate (ZnSO4) and zinc nano-fertilizer (ZnO NPs) was ...conducted with the aim to understand their effects on plant physiology. One-year old coffee plants were grown in greenhouse conditions and treated with two foliar applications of 10 mg/L of Zn as either zinc sulfate monohydrate (ZnSO4 ‧ H2O) or zinc oxide nanoparticle (ZnO NPs 20% w/t) and compared to untreated control plants over the course of 45 days. ZnO NPs positively affected the fresh weight and dry weight (FW and DW) of roots and leaves, increasing the FW by 37% (root) and 95% (leaves) when compared to control. The DW increase was 28%, 85%, and 20% in roots, stems, and leaves, respectively. The net photosynthetic rate increased 55% in response to ZnO NPs treatment at the end of experiment when compared to control. ZnO NPs-treated leaves contained significantly higher amounts of Zn (1267.1 ± 367.2 mg/kg DW) when compared to ZnSO4-treated plants (344.1 ± 106.2 mg/kg DW), while control plants had the lowest Zn content in the leaf tissue (53.6 ± 18.9 mg/kg DW). X-ray micro-analyses maps demonstrated the increased penetrance of ZnO NPs in coffee leaf tissue. Overall, ZnO NPs had a more positive impact on coffee growth and physiology than conventional Zn salts, which was most likely due to their increased ability to be absorbed by the leaf. These results indicate that the application of ZnO NPs could be considered for coffee systems to improve fruit set and quality, especially in areas where Zn deficiency is high.
•ZnO NPs easily penetrate the leaf surface, compared to traditional ZnSO4.•ZnO NPs have a positive role on plant growth and physiology compared to ZnSO4.•ZnO NPs may have a significant impact on coffee fruit set and quality.
Twist-3 collinear parton distribution functions (PDFs) are matrix elements of quark-gluon-quark or three-gluons light-cone operators. They depend on three momentum fraction variables, which are ...restricted to a hexagon region, and the evolution kernels are defined via two-dimensional convolution in these variables. We present the numerical realisation of the twist-3 evolution equations at leading order in the strong coupling for all kinds of twist-3 PDF (quark, gluon, chiral-even/odd, etc). We provide two independent codes (in C and Fortran) that have been extensively cross-checked, and are ready-to-use. We supplement the paper with a review of known properties of twist-3 PDFs.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
At the interface between two massless Dirac models with opposite helicity a paradoxical situation arises: a transversally impinging electron can seemingly neither be transmitted nor ...reflected, due to the locking between spin and momentum. Here we investigate this paradox in one spatial dimension where, differently from higher dimensional realizations, electrons cannot leak along the interface. We show that models involving only massless Dirac modes lead to either no solutions or to trivial solutions to the paradox, depending on how the helicity change across the interface is modeled. However, non trivial scattering solutions to the paradox are shown to exist when additional massive Dirac modes are taken into account. Although these modes carry no current for energies within their gap, their interface coupling with the massless modes can induce a finite and tunable transmission. Finally, we show that such massless + massive Dirac model can be realized in suitably gated spin–orbit coupled nanowires exposed to an external Zeeman field, where the transmission coefficient can be controlled electrically.
Bathymetry is considered an important component in marine applications as several coastal erosion monitoring and engineering projects are carried out in this field. It is traditionally acquired via ...shipboard echo sounding, but nowadays, multispectral satellite imagery is also commonly applied using different remote sensing-based algorithms. Satellite-Derived Bathymetry (SDB) relates the surface reflectance of shallow coastal waters to the depth of the water column. The present study shows the results of the application of Stumpf and Lyzenga algorithms to derive the bathymetry for a small area using an Unmanned Aerial Vehicle (UAV), also known as a drone, equipped with a multispectral camera acquiring images in the same WorldView-2 satellite sensor spectral bands. A hydrographic Multibeam Echosounder survey was performed in the same period in order to validate the method’s results and accuracy. The study area was approximately 0.5 km2 and located in Tuscany (Italy). Because of the high percentage of water in the images, a new methodology was also implemented for producing a georeferenced orthophoto mosaic. UAV multispectral images were processed to retrieve bathymetric data for testing different band combinations and evaluating the accuracy as a function of the density and quantity of sea bottom control points. Our results indicate that UAV-Derived Bathymetry (UDB) permits an accuracy of about 20 cm to be obtained in bathymetric mapping in shallow waters, minimizing operative expenses and giving the possibility to program a coastal monitoring surveying activity. The full sea bottom coverage obtained using this methodology permits detailed Digital Elevation Models (DEMs) comparable to a Multibeam Echosounder survey, and can also be applied in very shallow waters, where the traditional hydrographic approach requires hard fieldwork and presents operational limits.
Plant root traits are diverse and variable, and the way in which they interact has consequences for fundamental functions such as anchorage, or services such as soil fixation. Here, we characterize ...mechanical traits related to anchorage (tensile strength, strain, stiffness and toughness) at both intra‐ and inter‐specific levels and examine how they covary with other traits related to the root economics space. We grew twelve herbaceous species from contrasting taxonomical families in a common garden experiment. For each species, we excavated root systems and measured mechanical, morphological and chemical traits at two locations (proximal versus distal) for two root types (absorptive versus transport roots). At the intraspecific level, transport roots tended to be stronger and tougher than absorptive roots and could extend further before failure, but were as stiff as absorptiveroots. Where the root was sampled (proximalversus distal) had a limited effect on any root mechanical trait. The five monocots (Poaceae) had stronger and tougher root material than the seven dicots (Fabaceae, Plantaginaceae and Rosaceae), but there were no differences in stiffness. At the interspecific level, mechanical traits covaried positively and were strongly and positively correlated with specific root length (a trait related to the ‘do‐it‐yourself' soil exploration strategy), and negatively with root diameter (a trait related to the ‘outsourcing' soil exploration strategy) and root tissue density (a trait related to root lifespan). We demonstrate the important role of species' taxonomical subgroup (monocot versus dicot) and root type in governing mechanical trait variation at both intra‐ and inter‐specific levels. Our results can be regarded as the first evidence of a link between root mechanical robustness and the root economics space, through a strong association with the ‘do‐it‐yourself' soil exploration strategy.
Abstract
The topological phase of the Su–Schrieffer–Heeger (SSH) model is known to exhibit two edge states that are topologically protected by the chiral symmetry. We demonstrate that, for any ...parameter quench performed on the half-filled SSH chain, the occupancy of each lattice site remains locked to 1/2 at any time, due to the additional time-reversal and charge conjugation symmetries. In particular, for a quench from the trivial to the topological phase, no signature of the topological edge states appears in real-space occupancies, independently of the quench protocol, the temperature of the pre-quench thermal state or the presence of chiral disorder. However, a suitably designed local quench from/to a SSH ring threaded by a magnetic flux can break these additional symmetries while preserving the chiral one. Then, real-space effects of the quench do appear and exhibit different dynamical features in the topological and in the trivial phases. Moreover, when the particle filling is different from a half and the pre-quench state is not insulating, the dynamical appearance of the topological edge states is visible already in a chain, it survives time averaging and can be observed also in the presence of chiral-breaking disorder and for instantaneous quenches.
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